JPH04290183A - Bar code reader - Google Patents

Abstract

PURPOSE:To offer the bar code reader which can increase the read probability of bar code information as much as possible at low cost as to a bar code reader which is utilized for an information control system using bar codes. CONSTITUTION:The bar code reader is equipped with a bar code reading unit 36 which projects a light beam on a bar code passage area and scans the bar code with the deflected light beam while deflecting the light beam repeatedly along at least one of segments 42a, 42b, and 42c to read the bar code information optically. The device is equipped with a light beam returning and reducing means 40 which returns the light beam, emitted by the bar code reading unit 36 and passed through the bar code passage area once, to the bar code passage area at least once and also reduces the beam diameter of the light beam.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barcode reading device used in an information management system using barcodes. In recent years, information management systems using barcodes are not only limited to POS (Point of Seals) systems, but also OA (office automation) and FA (
It is also being introduced in fields such as factory automation), and there is a demand for the development of highly reliable barcode reading devices for reading barcode information.

0002

2. Description of the Related Art Referring to FIG. 11, a typical example of a barcode reader used in a POS system or the like is shown. A laser beam LB is emitted from this barcode reading window 10 as a light beam. The laser beam LB is repeatedly deflected to draw a predetermined scanning pattern 12 above the barcode reading window 10, and in this example, the scanning pattern 12 is
are three line segments 12a, 12b and 12 that intersect with each other.
formed by c.

A beam deflection optical system for deflecting the laser beam LB is arranged below the barcode reading window 10.
It is indicated in its entirety by the reference numeral 14. The beam deflection optical system 14 includes a bottom flat reflecting mirror 16 having a substantially fan-shaped configuration.
, a polygon mirror 18 which is arranged approximately at the center of the fan shape of the bottom plane reflecting mirror 16 and rotated at a constant speed clockwise by an appropriate motor;
three elongated flat reflecting mirrors 20a, 20b, and 20c arranged above the fan-shaped peripheral edge of No. 6;
A small flat reflecting mirror 24 placed at the center of the concave mirror 22 placed below the central elongated flat reflecting mirror 20b.
and includes. The laser beam LB is obtained from a suitable laser light source, such as a semiconductor laser 26, and the laser light generated there is first shaped into a predetermined cross-sectional shape by a beam shaping lens 28 and focused to a predetermined beam diameter to form a laser beam. Considered LB. Such a laser beam L
B is a beam deflection optical system 1 using a plane reflector reflector 30.
4, the laser beam LB emitted from the barcode reading window 10 follows the scanning pattern 12 as described above.
will be drawn.

Specifically, the laser beam LB is first made incident on a small plane reflecting mirror 24, and the laser beam L
B is reflected toward the rotating polygon mirror 18. When each reflective surface of the polygon mirror 18 crosses the laser beam LB heading toward it, the laser beam L
B is three long plane reflecting mirrors 20a, 20b and 20c.
are sequentially deflected along the respective elongated plane reflecting mirrors 20a,
The laser beam LB reflected by 20b and 20c is directed to the bottom flat reflector 16, and the laser beam LB reflected there is emitted to the outside through the barcode reading window 10. At this time, the long plane reflecting mirror 2
Laser beam LB deflected along 0a, 20b and 20c traces line segments 12a, 12b and 12c, respectively, thereby forming scanning pattern 12. In short, the laser beam LB is sequentially deflected along the line segments 12a, 12b and 12c by the polygon mirror 18 and the three elongated plane reflecting mirrors 20a, 20b and 20c.

When a barcode is read by the barcode reader as described above, an article bearing a barcode is held in the hand of an operator and passed above the barcode reading window 10. When the code is scanned by any of the laser beams deflected along line segments 12a, 12b and 12c, a portion of its reflected and scattered light is directed back along the exit optical path of the laser beam and enters the concave mirror 22. Then, it is detected by a photodetector 32 placed at the focal point of the concave mirror 22, and the detected information is processed by a barcode decoding circuit composed of a microcomputer or the like. In this case, it is determined whether or not the detection information, that is, the barcode information detected by the photodetector 32 is complete. If the barcode information is determined to be complete, for example, a signal sound is emitted, and this signal The sound informs the operator that reading of the barcode information is complete. On the other hand, if the barcode information is incomplete, i.e. if the barcode is not scanned or only partially scanned by any of the laser beams deflected along the line segments 12a, 12b and 12c, then Such a signal tone is not emitted, and the detected information is ignored as incomplete barcode information. At this time, the operator must repeatedly read the barcode while paying attention to the orientation of the barcode attached to the article until the above-mentioned signal sound is emitted.

Further, in order to read barcode information, reflected and scattered light of sufficient intensity is required, and for this purpose, the barcode must be scanned with a laser beam focused to a predetermined beam diameter. Such beam diameter is typically about 4
50 μm or less, and for this reason, the optical system of the barcode reader is configured to narrow down the beam diameter of the laser beam LB to the minimum at a predetermined height level above the barcode reading window 10. The range before and after the focus is defined as the barcode readable area. Referring to FIG. 12, such a readable range or read depth is indicated by the reference numeral L, and the read depth L is typically about 20
It is about cm. In short, the barcode must be read in the area of the minimum beam diameter of the laser beam LB, that is, in a range of about 10 cm before and after the focal point F.

As is clear from the above description, in order to reliably read the barcode information, it is necessary to completely scan the barcode with a laser beam focused to a predetermined beam diameter. In order to increase the probability of completely scanning a barcode with a laser beam, that is, the probability of reading barcode information, it is possible to use two barcode readers as shown in FIG. 11, as shown in FIG. Proposed. In this case, the two barcode readers are arranged such that their barcode reading windows 10a and 10b are, for example, at right angles to each other, and a laser beam is emitted from the barcode reading windows 10, 10 of each barcode reader. It is ejected along a predetermined scanning pattern. According to such a configuration, two scanning patterns are generated by two barcode readers in the barcode passage area, and the probability of reading barcode information is increased accordingly.

[0008] Conventionally, articles with barcodes attached thereto are conveyed along, for example, an endless belt conveyor, and the barcodes of the articles being conveyed are read by a barcode reader. In this case, as shown in FIG. 14, in order to increase the probability of reading barcode information, a plurality of barcode readers as shown in FIG. 11 are arranged along both sides of the endless belt conveyor 34, and each barcode reader is Laser beams are emitted from the barcode reading window 10 of the reader with different scanning patterns, thereby increasing the probability of reading the barcode information of each article.

[0009]

As is clear from the above description, conventionally it has been proposed to use a plurality of barcode readers in order to increase the probability of reading barcode information. The problem with such solutions is that they are expensive due to the use of multiple barcode readers. Furthermore, in the case of the conventional example shown in FIG. 14, even if multiple barcode readers are used,
Depending on the orientation of the barcode or where it is pasted, it may not be possible to read the barcode. For example, in the barcode reader arrangement shown in FIG. 14, it is difficult to read a barcode when the barcode is facing upward, and it is difficult to read the barcode when the barcode is facing downward. Barcode reading is not possible. Therefore, an object of the present invention is to provide a barcode reading device that can increase the probability of reading barcode information as much as possible at low cost.

0010

A barcode reading device according to the present invention emits a light beam into a barcode passage area and scans a barcode with the deflected light beam while repeatedly deflecting it along at least one line segment. a barcode reader for optically reading barcode information; and a light beam emitted from the barcode reader and once passed through the barcode passage area and returned to the barcode passage area at least once. It also includes a light beam returning and focusing means for narrowing down the beam diameter of the light beam to a diameter that allows barcode reading.

[0011]

[Operation] In the barcode reading device according to the present invention, the light beam emitted from the barcode reader and once passed through the barcode passing area is returned to the barcode at least once by the light beam return and aperture means. Since the beam diameter of the light beam is narrowed down to a diameter that allows barcode reading while being returned to the passage area, the probability of reading barcode information is increased even with just one barcode reader.

0012

[Example] Referring to FIGS. 1 and 2 of the attached drawings below,
An embodiment of a barcode reading device according to the present invention will be described.

First, referring to FIG. 1, one embodiment of a barcode reading device according to the present invention is shown, and this barcode reading device includes a barcode reader 36 as shown in FIG. A concave mirror 40 is disposed along one side of the barcode reading window 38 of the device 36 and mounted on a suitable support base. The laser beam emitted from the barcode reading window 38 is deflected on its upper surface to trace a scanning pattern 42, which scanning pattern 42 is formed by line segments 42a, 42b and 42c. That is, the laser beam is divided into line segments 42a and 42b.
and 42c, and therefore the scanning pattern 42 is also deflected sequentially along the horizontal plane above the barcode reading window 38.
A scanning pattern with a similar shape is formed. Further, the laser beam is focused to the minimum beam diameter at a predetermined height level above the barcode reading window 38, and as a result, there is a height range above the barcode reading window 38 in which the barcode information can be read, that is, a reading depth. Set. When an item with a barcode attached is held in the operator's hand and passed above the barcode reading window 38 from the direction of arrow A, if the barcode is facing downward, the barcode information is can be read.

In the embodiment shown in FIG. 1, the laser beam emitted from the barcode reading window 38 passes through the concave mirror 40.
At this time, the reflected laser beam is directed upstream of the barcode passage area as indicated by arrow A. Therefore, a similar scanning pattern is generated on the upstream side of the scanning pattern 42, and the scanning pattern is located approximately in a vertical plane. In FIG. 1, only a line segment 42b' forming such a scanning pattern in the vertical plane is shown, and this line segment 42b' corresponds to the line segment 42b forming the scanning pattern 42. What should be noted here is that when the laser beam is reflected by the concave mirror 40, the beam diameter of the laser beam is narrowed down to a diameter that allows the barcode to be read due to the concave mirror 40. Therefore, even if the barcode attached to the article being passed along the arrow A is directed toward the concave mirror 40, the barcode information can be read.

In the embodiment shown in FIG. 1, if it is difficult to design the optical system of the barcode reading device 36 so as to direct the laser beam emitted from the barcode reading window 38 toward the concave mirror 40, Reading window 3
A strip-shaped transmission diffraction hologram element may be pasted on the scanning pattern 42 along the line segments 42a, 42b, and 42c to diffract the laser beam toward the concave mirror 40. Furthermore, in the embodiment of FIG.
Although the concave mirror 40 stands upright with respect to the hologram reading window 38, the location and orientation of the concave mirror 40 may be changed as necessary.

Referring to FIG. 2, a modification of the embodiment shown in FIG. 1 is shown, in which a reflective diffractive hologram element 44 is used instead of the concave mirror 40; Affixed to a suitable support plate. The reflection type diffraction hologram element 44 has a characteristic of narrowing down the beam diameter when diffracting a laser beam incident thereon. When the laser beam emitted from the barcode reading window 38 enters the reflection type diffraction hologram element 44, the incident laser beam is diffracted toward the upstream side of the barcode passage area indicated by arrow A, and the diffracted laser beam The beam diameter of is narrowed down due to such characteristics. Also, as in the embodiment shown in FIG. 1, a scan pattern similar to scan pattern 42 is generated by the diffracted laser beam in a substantially vertical plane upstream thereof, thus providing a wide variety of possibilities for reading bar code information. You can get sex.

FIG. 3a shows a reflective diffractive hologram element 44.
An example of how to create is illustrated. In the figure, reference numeral 46 indicates a suitable transparent substrate coated with a photosensitive emulsion;
A diverging spherical wave is irradiated as a reference beam 48 on one side of the light beam, and a converging spherical wave is irradiated as an object beam 50 on the other side surface. Interference fringes generated by interference between the reference beam 48 and the object beam 50 are recorded on the photosensitive emulsion layer of the transparent substrate 46, and when the transparent substrate 46 is developed, a reflective diffractive hologram element 46' as shown in FIG. 3b is created. be done. Figure 3b
As shown in FIG. 3, when a diverging spherical wave is incident on the reflective diffraction hologram element 46' as the reproduction reference beam 48', the diffracted light 50' becomes convergent light. When such a reflection type diffraction hologram element 46' is used as the reflection type diffraction hologram element 44, even if the laser beam LB diverges and enters the reflection type diffraction hologram element 44 as shown in FIG. The beam LB' will converge toward a predetermined convergence point, the so-called focal point. As is clear from the example shown in FIG. 3a, the diffraction characteristics and convergence characteristics of the reflective diffraction element 44 can be set arbitrarily, which provides a large degree of freedom in the design of the barcode reading device.

Similar to the embodiment of FIG. 1, in the embodiment of FIG. A strip-shaped transmission diffraction hologram element may be pasted on the code reading window 38 along the line segments 42a, 42b, and 42c of the scanning pattern 42 to diffract the laser beam so as to direct it toward the concave mirror 40. Also, in the embodiment shown in FIG. 2, the reflection type diffraction hologram element 44 is placed upright with respect to the hologram reading window 38, but its location and installation angle may be changed as necessary.

Referring to FIG. 5, there is shown an embodiment of a barcode reading device used when barcoded articles are conveyed by the endless belt conveyor 52, and this embodiment is similar to the embodiment shown in FIG. It corresponds to this. The barcode reader 36 and the concave mirror 44 are arranged on both sides of the endless belt conveyor 52 across the upper running portion of the endless belt, and the barcoded articles are conveyed along the direction indicated by arrow A. The laser beam emitted from the barcode reading window 38 of the barcode reader 36 is deflected so as to draw a scanning pattern 42, and when the laser beam enters the concave mirror 40, the barcode passing area indicated by the arrow A is formed by the concave mirror 40. The reflected laser beam also creates a scanning pattern 42.
A scanning pattern similar to that is drawn. Furthermore, since the beam diameter of the reflected laser beam is narrowed down by the concave mirror 40, it is also possible to read barcode information using the reflected laser beam. In short, for barcodes directed toward the barcode reader 36, the barcode reading window 3
The bar code directed toward the concave mirror 40 can be read by the laser beam reflected from there.

FIG. 6 shows a modification of the embodiment shown in FIG. 5, the relationship between these two embodiments being similar to that between the embodiment of FIG. 1 and the embodiment of FIG. . That is, in the embodiment of FIG. 6, a reflection type diffraction hologram element 44 is used in place of the concave mirror 40, and this reflection type diffraction hologram element 44 directs the laser beam incident thereon upstream of the barcode passage area indicated by arrow A. It has the property of diffracting the laser beam toward the side and narrowing down the beam diameter of the diffracted laser beam. A scanning pattern similar to the scanning pattern 42 is also drawn on the upstream side by such a diffraction laser beam, and barcode information can be read using that scanning pattern, as in the case of the embodiment shown in FIG. .

In the embodiments shown in FIGS. 5 and 6, the reflected or diffracted laser beam was directed upstream of the barcode passage area indicated by arrow A, but it could also be directed downstream. Needless to say, it's a good thing. In the embodiments of FIGS. 5 and 6, the laser beam emitted from the barcode reading window 38 of the barcode reader 36 may be directed downward or upward, or the reflected or diffracted laser beam may be directed downward or upward. It is also possible to have the barcode facing upward, and in this case, it is possible to read the barcode information even when the barcode is facing upward or downward. Note that when an article with a barcode attached has a complicated shape, the barcode may be oriented downward.

Referring to FIG. 7, an embodiment is shown that is a development of the embodiment shown in FIG. Arranged to extend along both sides of the upper run of the endless belt, both reflective diffractive hologram elements 54 and 56 are affixed to a suitable support plate. The laser beam emitted from the barcode reading window 38 of the barcode reader 36 is deflected along the scanning pattern 42 as in the above embodiment, and the deflected laser beam first passes through the first reflective diffraction hologram. The incident laser beam is incident on element 54 as shown by arrow A.
The light beam is diffracted upstream of the barcode passage area and toward the second reflective diffractive hologram element 56 . The laser beam incident on the second reflection type diffraction hologram element 56 is then directed again upstream of the barcode passage area indicated by arrow A and onto the first reflection type diffraction hologram element 5.
The laser beam that is diffracted toward the first reflection type diffraction hologram element 54 is further diffracted toward the upstream side of the barcode passage area indicated by arrow A. The first and second reflective diffractive hologram elements 54 and 56 are also the reflective diffractive hologram elements 4 described above.
As in case 4, the beam diameter of the laser beam is narrowed down, and therefore barcode information is transmitted by the laser beam diffracted by the first and second reflection type diffraction hologram elements 54 and 56, respectively. It is possible to read. According to the embodiment shown in FIG. 7, the probability of reading barcode information is increased because the laser beam is diffracted or deflected more variously.

In the embodiment shown in FIG. 7, the barcode reader 36 is placed upstream of the first and second reflective diffraction hologram elements 54 and 56, and the laser beam emitted therefrom is passed between them. Needless to say, it is also possible to cause the light to be diffracted toward the downstream side, and the barcode reader 36 can also be installed on the first reflective diffraction hologram element 54 side. Furthermore, in the embodiment of FIG. 7, it is also possible to cause the diffraction to be repeated at least four times or more between the first and second reflection type diffraction hologram elements 54 and 56, and in this case, depending on the number of diffraction times, the first and second reflection hologram elements 54 and 56 It is also possible to divide the two reflection type diffractive hologram elements 54 and 56 into a plurality of regions, and make the diffraction characteristics of each divided region different. For example, the laser beam may be diffracted in such a manner as to be confined between the first and second reflective diffractive hologram elements 54 and 56;
In this case, since the deflection of the laser beam becomes more diverse, the probability of reading barcode information can be increased accordingly. In addition, the first and second reflection type diffraction hologram elements 5
The laser beam is transferred between endless belt conveyor 5 and 56.
The upper running part of the endless belt shown in No. 2 may be diffracted downward or downward. In this case, even if the barcode is facing upward or downward, the barcode will be diffracted. The possibility of reading information is also provided.

Referring to FIG. 8, there is shown an embodiment that is a further development of the embodiment shown in FIG.
A reflective diffractive hologram element 58 is disposed above the upper run of the endless belt of the endless belt conveyor 52 and between the first and second reflective diffractive hologram elements 54 and 56. That is, the third reflection type diffraction hologram element 58 is affixed to the underside of a suitable support plate spanned between the support plates of the first and second reflection type diffraction hologram elements 54 and 56. Of course, the third reflection type diffraction hologram element 58 also has the characteristic of narrowing down the beam diameter of the laser beam. Barcode reader 3
The laser beam emitted from the barcode reading window 38 of No. 6 is first incident on the first reflection type diffraction hologram element 54, and the incident laser beam is directed toward the second or third reflection type diffraction hologram element 56, 58. After being diffracted toward the beam, the beam is repeatedly diffracted between the first, second, and third reflection type diffraction hologram elements 54, 56, and 58, and the diffraction order in this case can be arbitrarily selected. According to the embodiment shown in FIG. 8, the diffraction direction, that is, the deflection direction of the laser beam is made even more diverse, so that the probability of reading barcode information is greatly increased.

In the embodiment of FIG. 8, the fourth reflective diffraction hologram element may be affixed to the endless belt surface of the endless belt conveyor 52 or may be formed on the endless belt surface itself; The reflective diffractive hologram element is also provided with properties that allow it to narrow down the beam diameter of the laser beam. In this case, since the laser beam is diffracted left, right, up and down, the diffraction directions, that is, the deflection directions of the laser beam can be made more diverse and complex, and the probability of reading barcode information increases accordingly. In the embodiment of FIG. 8, the laser beam is emitted from the barcode reading window 38 of the barcode reader 36 toward the first reflective diffraction hologram element 54, but if necessary, the laser beam may be emitted from the third reflective diffraction hologram element 54. type diffraction hologram element 58
It may also be fired towards.

Referring to FIG. 9, an embodiment is shown which is a further development of the embodiment shown in FIG. 8, in which the endless belt of the endless belt conveyor 52 is formed of a transparent material; A suitable support plate is arranged on the lower side of the upper run, on which the fourth reflective diffraction hologram element 60 is pasted. Barcode reader 36
The laser beam emitted from the barcode reading window 38 is first incident on the first reflection type diffraction hologram element 54, and the incident laser beam is directed toward the second, third or fourth reflection type diffraction hologram element 56. , 58, 60
The first, second, third and fourth
reflective diffractive hologram elements 54, 56, 58 and 6
It is repeatedly diffracted between 0 and 0. A noteworthy feature of such a configuration is that the laser beam can pass through the upper running portion of the transparent endless belt of the endless belt conveyor 52 from the bottom to the top, so that the barcode can be printed on the surface of the transparent endless belt. The point is that the barcode information can be read even if the barcode is facing downward so as to make contact.

In the embodiment of FIG. 9 as well, it is not necessary to emit the laser beam from the barcode reading window 38 of the barcode reader 36 toward the first reflective diffraction hologram element 54; It may be ejected onto reflective diffractive hologram elements 58,60. Additionally, in the embodiment of FIG. 9, the barcode reader 36 may be placed below the transparent endless belt of the endless belt conveyor 52, in which case the laser beam passes through the transparent endless belt to the first, second or Third reflective diffractive hologram element 56
, 58, 60. If the laser beam diverges beyond the readable beam diameter, use an optical element that converges the laser beam, such as a reflective or transmissive hologram element that narrows down the beam diameter, a convex lens, or a concave mirror. It is also possible to interpose the code reader 36 and the upper running part of the transparent endless belt.

Referring to FIG. 10, there is shown yet another embodiment of a bar code reading device according to the present invention, which also uses an endless belt conveyor as in the embodiments shown in FIGS. 5 to 9. 52, the bar code attached to the article being conveyed is read, but the embodiment differs from the embodiments shown in FIGS. 5 to 9 in the following points. That is, the barcode reader 62 used in this embodiment
In this case, the laser beam emitted from the barcode reading window 64 is repeatedly deflected only along a single line segment 66, and the laser beam emitted from the barcode reading window 64 is repeatedly deflected only along a single line segment 66, and the laser beam emitted from the barcode reading window 64 is repeatedly deflected along a single line segment 66. The second reflection type diffraction hologram elements 68 and 70 not only have the property of narrowing down the beam diameter of the laser beam, but also have the property of rotating the deflection direction of the diffraction laser beam by an appropriate angle. As shown in FIG. 10, a laser beam deflected along a line segment 66 and emitted from the barcode reading window 64 of the barcode reader 62 is directed to the first reflective diffraction hologram element 68.
When the diffracted laser beam is incident on and diffracted, the deflection direction of the diffracted laser beam is rotated as indicated by the reference numeral 66', and the deflection direction of the diffracted laser beam diffracted by the second reflective diffractive hologram element 70 is rotated. is also rotated. In this embodiment, while the laser beam is repeatedly diffracted between the first and second reflective diffraction hologram elements 68 and 70, the deflection direction of the laser beam is at least 360°. Bar code information directed to either of the reflective diffractive hologram elements 68 and 70 will be readable. Generally speaking, the denser the interference fringes of the diffraction hologram element, the greater the diffraction effect, so the line segment that deflects the laser beam (
For example, if the interference fringes change from dense to coarse or from coarse to fine along the line segment 66', it is possible to rotate the deflection direction of the laser beam that is deflected and diffracted along the line segment. Become.

In the embodiment shown in FIG. 10, both the first and second reflection type diffraction hologram elements 68 and 70 are given the characteristic of turning the deflection direction of the diffracted laser beam by an appropriate angle; Such characteristics may be provided only to the reflection type diffractive hologram element. In addition, in the embodiment of FIG. 10, it is also possible to use the barcode reader 36 used in FIGS.
Since the laser beam diffracted between 8 and 70 is deflected in more diverse directions, the probability of reading barcode information is further increased. On the other hand, at least one of the reflection type diffraction hologram elements used in the embodiments of FIGS. 2 and 5 to 9 may be given a characteristic of rotating the deflection direction of the laser beam, and in this case, the deflection direction of the laser beam may be It becomes possible to make the information more diverse and complex, and the probability of reading barcode information is further increased.

[0030]

[Effects of the Invention] As is clear from the above description, according to the present invention, the probability of reading barcode information can be greatly increased by using only one barcode reader. It becomes possible to construct an information management system at low cost, which can greatly contribute to its widespread use.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of a barcode reading device according to the present invention.

FIG. 2 is a schematic perspective view showing a modification of the barcode reading device shown in FIG. 1;

FIG. 3 is an explanatory diagram illustrating a production example of a reflection type diffraction hologram element used in the barcode reading device shown in FIG. 2 and its characteristics.

FIG. 4 is an explanatory diagram illustrating the aperture effect of the beam diameter of the laser beam when the laser beam is diffracted by the reflection type diffraction hologram element shown in FIG. 3b.

FIG. 5 is a schematic perspective view showing another embodiment of a barcode reading device according to the present invention.

6 is a schematic perspective view showing a modification of the barcode reading device shown in FIG. 5. FIG.

7 is a schematic perspective view of a further developed embodiment of the barcode reading device shown in FIG. 6. FIG.

8 is a schematic perspective view of a further developed embodiment of the barcode reading device shown in FIG. 7. FIG.

9 is a schematic perspective view of a further developed embodiment of the barcode reading device shown in FIG. 8. FIG.

FIG. 10 is a schematic perspective view showing yet another embodiment of the barcode reading device according to the present invention.

FIG. 11 is a schematic perspective view illustrating a conventional barcode reader that can be used in the barcode reader according to the present invention.

FIG. 12 is an explanatory diagram illustrating the reading depth of a laser beam for reading a barcode.

FIG. 13 is a schematic perspective view showing a conventional barcode reading device.

FIG. 14 is a schematic perspective view showing another type of conventional barcode reading device.

[Explanation of symbols]

36...Barcode reader 38...Barcode reading window 40...Concave mirror 42...Scanning pattern 42a...Line segment 42b...Line segment 42c...Line segment 44...Reflection type diffraction hologram element 52...Endless belt conveyor 54...First reflection type Diffraction hologram element 56...Second reflection type diffraction hologram element 58...Third reflection type diffraction hologram element 60...Fourth reflection type diffraction hologram element 62...
Barcode reader 64...Barcode reading window 66...Line segment

Claims (15)

[Claims] 1. A light beam is emitted into a barcode passage area and at least one line segment (42a, 42b,
A barcode reader (32, 62) that optically reads barcode information by scanning the barcode with a deflected light beam while repeatedly deflecting the light beam along 42c, 66).
Then, the light beam emitted from the barcode reader (32, 62) and once passed through the barcode passing area is returned to the barcode passing area at least once, and the beam diameter of the light beam is changed by changing the beam diameter. Light beam return and aperture means to narrow down the diameter to a code readable diameter (40:44
:54:56:58:60:68, 70). 2. The barcode reading device according to claim 1, wherein the light beam returning and aperture means comprises a concave mirror (40) disposed at a predetermined position along the barcode passage area.
) A barcode reading device comprising: 3. The barcode reading device according to claim 1, wherein the light beam returning and aperture means comprises a reflection type diffraction hologram element (44:54:56: 58:60, 68,
70) A barcode reading device comprising: 4. The barcode reading device according to claim 3, wherein the reflection type diffraction hologram element (68, 7
0) has a characteristic of rotating the deflection direction of the deflected light beam by a predetermined angle. 5. The optical deflection device according to claim 1, wherein the barcode passage area is formed by a conveying means (52) for moving an article bearing a barcode,
the light beam return and aperture means comprises first and second reflective diffraction hologram elements (54, 56: 68, 70) arranged along both sides of the barcode passage area;
These first and second reflection type diffraction hologram elements (5
4, 56: 68, 70) A bar code reading device characterized in that a light beam is diffracted at least twice between 6. The barcode reading device according to claim 5, wherein at least one of the first and second reflection type diffraction hologram elements (68, 70) rotates the deflection direction of the deflected light beam by a predetermined angle. A barcode reading device characterized by having characteristics that allow 7. The light deflection device according to claim 5, wherein the light beam return and aperture means further comprises a third reflective diffraction hologram element (58) disposed along the upper side of the barcode passage area. and the first, second and third reflective diffractive hologram elements (54, 56, 58).
A barcode reading device characterized in that a light beam is diffracted at least three times between the two. 8. The barcode reading device according to claim 7, wherein at least one of the first, second and third reflection type diffraction hologram elements (54, 56, 58) A barcode reading device characterized by having a characteristic of rotating the barcode by a predetermined angle. 9. The light deflection device according to claim 5, wherein the conveying means is formed as an endless belt conveyor (52) with an endless belt, and the bar code passing area is provided by an upper running part of the endless belt. , the light beam return and aperture means further includes a fourth reflective diffractive hologram element formed on the surface of the endless belt, and the first, second, third and fourth reflective diffractive hologram elements Between (54, 56, 58) the light beam is at least 4
A barcode reading device characterized by being diffracted more than once. 10. The barcode reading device according to claim 9, wherein at least one of the first, second, third and fourth reflective diffraction hologram elements (54, 56, 58, 60) A barcode reading device characterized by having a characteristic of rotating the deflection direction of a light beam by a predetermined angle. 11. The light deflection device according to claim 5, wherein the conveying means is formed as an endless belt conveyor (52) having an endless belt made of a transparent material, and the bar code passage area is located above the endless belt. provided by the optical beam return and aperture means further includes a fourth reflective diffractive hologram element (60) disposed along the underside of the upper running portion of the endless belt; 2
, third and fourth reflective diffractive hologram elements (54,
56, 58, 60), wherein a light beam is diffracted at least four times or more. 12. The barcode reading device according to claim 11, wherein at least one of the first, second, third and fourth reflective diffraction hologram elements (54, 56, 58, 60) A barcode reading device characterized by having a characteristic of rotating the deflection direction of a light beam by a predetermined angle. 13. The light deflection device according to claim 5, wherein the conveying means is formed as an endless belt conveyor (52) having an endless belt made of a transparent material, and the bar code passage area is located above the endless belt. 1. A barcode reading device, characterized in that the deflected light beam is introduced into the barcode passage area from below the upper running part of the endless belt and through it. 14. The barcode reading device according to claim 13, wherein the light beam return and aperture means further comprises a fourth reflective diffraction hologram element disposed along the lower side of an upper running portion of the endless belt. (60), wherein the light beam is diffracted at least four times between the first, second, third and fourth reflection type diffraction hologram elements (54, 56, 58, 60). barcode reader. 15. The barcode reading device according to claim 14, wherein at least one of the first, second, third and fourth reflective diffraction hologram elements (54, 56, 58, 60) A barcode reading device characterized by having a characteristic of rotating the deflection direction of a light beam by a predetermined angle.